Handheld electronic devices continue to become more prevalent and advanced. One of the features that continues to evolve is the navigation system of the handheld electronic device. Several navigation tools have been used including trackwheels, 4-way navigational pads, and joysticks. In the present description, a trackball is disclosed as a navigational tool.
The use of a trackball presents challenges and advantages not before experienced in the design of navigational tools. Current technology for trackballs utilizes pairs of sensors located about the trackball for sensing rotational motion of the trackball which is representative of the desired direction the user would like the cursor to move on the screen. The trackball is also equipped with a sensor for detecting that a selection is being made by the user depressing the trackball.
Furthermore, handheld electronic devices are evolving into smaller entities. With each new generation, these devices possess greater functional capabilities and are more responsive to the daily needs of their users. As reliance upon these devices grows, the user demands immediate access to them. Consequently, users are inclined to carry them in their pockets.
Since the trackball is exposed and rotates freely, it is susceptible to unintentional and usually undesirable rotation. As an example, this can occur when the user places the handheld electronic device in his or her pocket and the rubbing of the fabric against the trackball causes unintentional rolling of the trackball. The undesirable nature of this occurrence is at least partly attributable to the fact that actuation of a device's navigation tool traditionally restores power to the screen (after having entered a sleep mode) because it is usually interpreted as an indication that the user wants to use the device in some capacity. Therefore, if the trackball is frequently unintentionally actuated, the screen will be lit unnecessarily, wasting battery power.
As described above, in the instance of a trackball being used as the navigation tool, sensors are required to detect motion of the trackball. Therefore, in order to be able to detect rollerball motion indicative of desired use, the sensors must always be powered-on which consumes energy and reduces the energy savings experienced because the screen has been put into sleep mode.
In response to these needs and deficiencies, the presently presented solutions have been developed in order to avoid the unnecessary consumption of power in handheld devices that utilize trackball navigation tools.